import os
source_file = input('请输入要打开的文件名:')
src= open(source_file,mode='r',encoding='utf8')
content = src.read()

filename,extetion = os.path.splitext(source_file)
target_file = filename + '-副本' + extetion
target = open(target_file,mode='a',encoding='utf8')
target.write(content)

src.close()
target.close()



